What does it all mean? According to Rice University political scientist Mark Jones, the bottom line is that it’s “a very competitive race, with both Cruz and Dewhurst having a realistic chance of victory.”

Jones and SMU political scientist Cal Jillson both said internal polls should be viewed cautiously.

Jones advised “a very healthy dose of skepticism.”

Jillson, when I asked him about the polls released Thursday showing an advantage for Cruz, said, “Every campaign can produce polls showing they are moving up fast or leading. It is campaign malpractice not to have such polls late in the race. I continue to think that Dewhurst will win the runoff by six or eight points.”

The PPP poll is the only one that can be considered objective, Jones said, but its results are “slightly biased in Cruz’s favor due to the screening question which limited the survey respondents to only those individuals who say they definitely will vote in the runoff.”

“Given that Cruz supporters tend to be more enthusiastic and motivated to turn out for their candidate then Dewhurst supporters, the survey is likely excluding a population of potential voters, some of whom will vote in the runoff, who as a group at least slightly favor Dewhurst over Cruz,” Jones said.

Despite that, he said, the results constitute “great news for Cruz” because the poll shows his candidacy is “extremely viable, something that will both fire up his base as well as garner additional financial backing for his campaign.”

Some others question the PPP’s use of an automated telephone survey.

Jones said get-out-the-vote efforts and TV air wars will help revive interest in the race in the runup to the July 31 runoff, predicting turnout of 750,000 to 1 million “with the higher the number, the better the odds of a Dewhurst victory.”